The present invention relates to a loom operating apparatus and method whereby a loom is started up without having a contact circuit switch the winding connection of the loom motor so as to prevent a staggered weave in the start-up stage.
One known method for starting a loom, as disclosed in Japanese Patent Laid Open No. 60-50899, involves bringing the loom motor windings into a delta connection upon start-up and switching the windings to a star connection at the completion of the start-up stage. This prior art method is called the stagger-free starting method.
More specifically, a low level of loom motor torque upon start-up would produce a weak beating force immediately after the start-up, resulting in a staggered weave. According to the above prior art method, a rated voltage times the square root of three (3) is applied upon start-up to the motor windings to make the torque higher than rated. At the completion of the start-up stage, the torque is reduced to the rated value, thereby effectively preventing the staggered weave from occurring. To switch the motor windings from delta connection to star connection requires installing a star connection contactor and a delta connection contactor. The star connection contactor short-circuits one-side ends of three independent windings, and the delta connection contactor brings the motor windings into a ring-like connection. The delta connection contactor is activated immediately after start-up. At the completion of the start-up stage, the delta connection contactor is deactivated and the star connection contactor is activated.
Under the above prior art method, as described, the main circuit must comprise the star and delta connection contactors for motor winding switchover. This necessarily entails a number of disadvantages associated with contact circuits such as contact wear and spark generation. Furthermore, the circuit switchover involves a time period in which the loom motor is not powered, which may provide another source for causing a staggered weave.